Referring to FIG. 1, Taiwanese Utility Model Patent No. M414589 discloses a conventional earthquake detecting device 1 that includes, among others, a sensing unit 11, a warning unit 12 which is operable to output sound and light, and a processing unit 13 which is coupled to the sensing unit 11 and the warning unit 12. The sensing unit 11 is adapted for sensing shaking of the conventional earthquake detecting device 1 due to, for example, earthquakes, and includes an accelerometer 111 and a gyroscope 112. The processing unit 13 receives signals generated by the accelerometer 111 and the gyroscope 112, uses extended Kalman filtering (EKF) to estimate intensity of the shaking based on the received signals, and controls the warning unit 12 to alert people by outputting sound and light when the estimated intensity exceeds a predetermined threshold.
However, movement of the conventional earthquake detecting device 1 from one location to another location will result in false warnings, and therefore it is only suitable to place the conventional earthquake detecting device 1 in a fixed location. In addition, the EKF, a rather complex calculation, requires the processing unit 13 to have high computation power, otherwise the conventional earthquake detecting device 1 would be overwhelmed by high calculation burden.